Clonal Diversity and Sex Ratio of a Malaria Parasite

疟疾寄生虫（疟原虫）具有复杂的生命周期，包括脊椎动物宿主（包括人类和许多野生动物物种）血细胞内的无性生殖（细胞分裂）和吸血昆虫内的有性生殖。寄生虫在血细胞中产生雄性和雌性性细胞（配子体），这些细胞在昆虫体内交配。尽管人们对疟原虫的生命周期已经了解了世纪，但有一个特征仍然是个谜：为什么配子体性别比例在疟原虫物种之间，甚至在任何一个物种的感染之间都是不同的。这项研究将是第一个研究自然疟疾系统的分子遗传学，以测试性别比例理论，进化生物学的支柱。它将研究寄生虫的遗传多样性如何影响雄性和雌性配子体的比例（性别比），实验使用疟原虫感染爬行动物宿主。这些实验将检验这一假设，即配子体的性别比例是由遗传上相同的配子体之间发生交配的频率决定的。这些实验还将检验寄生虫能够监测单个感染个体内亲属和非亲属的存在的假设。疟疾每年造成数百万人死亡，是许多野生动物的重要疾病。寄生虫的遗传多样性被认为在其生物学中起主要作用，包括传播和毒力，因此本研究的结果可能为治疗这种疾病提供重要信息。此外，该项目还将培训至少10名本科生和研究生。

Malaria parasites (Plasmodium) have a complex life cycle that consists of asexual reproduction (cell division) within the blood cells of vertebrate hosts (including humans and many wildlife species), and sexual reproduction within a blood-feeding insect. The parasites produce male and female sex cells (gametocytes) in blood cells, and these mate within the insect. Although the life cycle of the malaria parasite has been known for a century, one feature remains a mystery: why gametocyte sex ratio varies among Plasmodium species and even among infections for any one species. This study will be the first to study the molecular genetics of a natural malaria system to test sex ratio theory, a mainstay of evolutionary biology. It will examine how the genetic diversity of the parasite influences the ratio of male and female gametocytes (sex ratio), with experiments using a Plasmodium that infects a reptile host. The experiments will test the hypothesis that the sex ratio of those gametocytes is determined by how often matings occur between gametocytes that are genetically identical. The experiments will also test the hypothesis that the parasites are able to monitor the presence of kin and non-kin within a single infected individual. Malaria kills millions of people every year and is an important disease of many wild animals. The genetic diversity of parasites is thought to play a major role in their biology, including transmission and virulence, so the results of this study may provide important information for treating this disease. In addition, this project will result in the training of at least 10 undergraduate and graduate students.